Communication system



Patented Jan. 11, 1944 UNITED STATES i ATENT OFFICE COMMUNICATION SYSTEMApplication August 4, 1942, Serial No. 453,536

5 Claims.

This invention relates to communication systems and particularly tospecial service telephone systems.

The object of the invention is to provide means 1" or changing thenormal switching arrangement of a subscriber's line so that unwantedincoming calls may be diverted while still providing normal outgoingservice. Under certain traffic conditions it sometimes happens that theload of incoming service increases to the point where seriousinterference with the use of a line for outgoing service is established.Where it is important that outgoing service be maintained the presentarrangement will provide means for temporarily rearranging the switchingfacilities so that all incoming calls will be diverted to a specialoperator. At the same time the line is switched to another lineappearance so that the subscriber may have normal outgoing service.Furthermore, this other line appearance may be in th nature of anunlisted number known only to those whom it is important to haveincoming service to the line.

In its simplest form the present invention consists of a relay formingpart of an auxiliary line circuit under manual control of a responsibleperson such as 2. BSA operator. Upon proper orders the DSA operator willplace this relay in operation whereupon the normal line appearance ofthe listed line will be disconnected from the subscribers line andconnected to a line extending to an intercepting operators position, sothat normally directed trafiic Will flow to the intercepting operatorinstead of to the subscribers line. At the same time the subscribersline is switched to an unlisted line appearance so that normal outgoingservice may be had and emergency incoming service provided for thoseentrusted with the actual number of such unlisted line appearance.

In an alternative lorm of the invention the subscribers line ispermanently connected to an unlisted or secret point of access to theline whereby trusted individuals may gain access to the line at alltimes. t the same time the line is connected to a listed point of accessso that the public may gain access to the line in the regular WayvHowever, means is provided so that if the line becomes overburdened withcalls by the listed number that point of access may be cut oh" anddiverted to an intercepting operators position so that the line may onlybe reached by way of the unlisted number. Outgoing service from the linemay be had at all times through diagram, somewhat schematic in characterbut showing the essential features of the invention in detail.

Fig. 1 shows a circuit diagram in which the line is normally associatedwith a listed number termination in the switching apparatus which may bediverted to an intercepting operators position while the line itself isswitched to an unlisted number termination.

Fig. 2 shows a circuit diagram in which the line is permanentlyconnected to an unlisted number termination over which the line can atall times be reached. The line is also connected normally to a listednumber termination in such manner that such termination may be cut edand diverted to an intercepting operators position.

A subscribers station I is extended from a central ofiice overconductors 2 and 3. Normally these conductors are connected through thecontacts of a relay 4 to conductors 5 and 6, respectively, which lead tothe incoming and outgoing switching facilities for line number 1234, byway of example. The subscriber at station I will then be listed in thedirectory as having telephone number 1234. If the incoming calls to thislisted number become too numerous and interefere with the outgoingservice from station I, then the subscriber thereat may notify the DSAoperator that he wishes the normal trafiic to be diverted. The DSAoperator will then operate key I to operate relay 4. As long as key 1 isoperated and relay 4 responds the signal lamp 8 associated with the key1 will burn as a signal that the service to the subscriber listed undertelephone number 1234 is on an emergency basis. At this time the lineconductors 2 and 3 will be disconnected from the line conductors ii andi3 and transferred to conductors 9 and it associated with the switchingfacilities for line number 5678. This line number will not be listed butmay be known to persons to whom it is important to establishcommunication with the subscriber at station I. This subscriber, ofcourse, can have outgoing service from station i over the regularfacilities of line 5678.

Incoming service toward the subscriber at station i will be provided byconnection established between conductors and 6 and conductors II andI2, respectively, leading to an intercepting operators position. On anincoming call ringing current flowing through thermistor I3, upperwinding of relay l4 and condenser l5 will first heat up the thermistoruntil sufficient current flows through relay M to cause its operation.Relay M then locks through its lower winding to the back contact ofarmature 3 of relay l6 and lights the ignal lamp I1. When theintercepting operator, who may be the DSA operator, answers the call byplugging into jack I8, the relay I6 is operated. A bridge circuit closedby armature l of relay it trips the machine ringing over line 1234 andthe operator then communicates with the calling subscriber.

While this invention has been illustrated in a simple manner it will beunderstood that the principle may be applied in a variety of ways. Theline extending to the substation i may be one of a large group serving aprivate branch exchange and like facilities may be given to other linesof such a group so that a subgroup of lines within such group may beheld free of the normal incoming traffic.

Fig. 2 shows an alternative arrangement. Here the station it isconnected to the central oilice by the line conductors 2i and 2t. Theusual line and cut oif relay arrangement for initiating outgoing serviceis indicated by the rectangle 22 and the usual line-finder arrangementis indicated by the brushes 23, 24 and 25. The line extends through thecontacts of relay 26 to the final multiple designated as the listednumber LIberty 1234, over which the line may be reached by the publicgenerally. The tip ring and sleeve conductors 21, 23 and 29,respectively, are also permanently connected to the final multipledesignated as the unlisted number VIcto-ry 5678. It will be noted thatthe listed and unlisted numbers may belong in different exchanges sothat the unlisted number may even be more difiicult of detection than ifboth were in the same exchange.

The unlisted number will be known only to trusted individuals who mayhave need to reach the station H3 at any time. If the traffic over theterminals reached by the listed number becomes too great or if there isspecial need to i hold the line open for calls over the unlisted numberthe DSA operator will be instructed to operate the key 3b, which willresult in the operation of relay 26. Thereupon the listed numberterminals will be disconnected from the line w leading to station it andconnected to the intercepting operators position indicated by jack 3iand lamp During the operation of relay 2d, signal lamp 33 will burnsteadily as an indication to the DSA operator that the associated lineis on an emergency basis.

If during this interval a call should come in over the listed numberterminals the ground on the sleeve will operate relay 34 which changesthe steady burning of lamp 33 to a flashing signal controlled by theinterrupter 35. At the same time relay M will lock relay 26 so that ifkey 3% should be returned to its normal position while the interceptingoperator is in communication with a calling party, such connection willnot be broken and the party at station l9 disturbed.

The operation of the intercepting operators circuit is the same in botharrangements.

What is claimed is:

1. In a communication system, switching means for interconnecting aplurality of lines, lines appearing in said switching means, a listednumber line, an unlisted number line, a subscribers station, saidstation being normally accessible over said listed number line, aninter" cepting operators line, means for switching said listed numberline from said subscriber station to said intercepting operators line,and means for establishing a connection to said station over saidunlisted number line.

2. In a communication system, switching means for interconnecting aplurality of lines, a subscriber station, lines appearing in saidswitching means, a first and a second line appearance in said switchingmeans individual to said subscriber station, an intercepting operatorsline, and operator controlled means for diverting calls over one of saidline appearances from said subscriber station to said interceptingoperators line.

3. In a communication system, switching means for interconnecting aplurality of lines, lines appearing in said switching means, a listednumber line, a relay, a subscribers line normally connected through saidrelay to said listed number line, an intercepting operators line, anunlisted number line, and means controlled by said relay fortransferring said subscribers line from said listed number line to saidunlisted number line and for connecting said listed number line to saidintercepting operators line.

4. In a communication system, machine switching means forinterconnecting a plurality of lines, lines appearing in said switchingmeans, an operators position for extending connections to said lines, asubscribers line, a listed number line normally connected to saidsubscribers lino, switching control means associated with said line, anunlisted number line, a line extending to said operators position, andmeans controlled by said switching control means for transferring saidsubscribers line from connection with said listed number line toconnection with said unlisted number line and for transferring saidlisted number line from connection with said subscribers line toconnection with said line extending to said operators position.

5. In a communication system, machine switching means forinterconnecting a plurality of lines, lines appearing in said switchingmeans, a subscribers line, a listed number line, an unlisted numberline, said subscribers line being normally connected to said listednumber line for normal incoming and outgoing service over said switchingmeans, and means for transferring said subscribers line from connectionwith said listed number line to connection with said unlisted numberline for normal outgoing service from said subscribers line and foremergency incoming service to said subscribers line.

ALOYSIUS J. BUSCH. ISRAEL H. HENRY.

